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Introduction

BACKGROUND FOR THE STUDY

Seafood is considered a healthful food choice—it is a source of high-quality protein, long-chain polyunsaturated fats, and essential micronutrients such as vitamin D, selenium, and iodine. In this report, seafood includes marine and freshwater fish, mollusks, and crustaceans. The Dietary Guidelines for Americans 2020–2025 (DGA¹) recommends that U.S. adults eat at least 8 ounces (oz) of seafood per week, with lower total amounts for children in proportion to their overall energy intake. Individuals who are pregnant or breastfeeding are advised to consume 8–12 oz of seafood per week, and to choose options lower in mercury. The DGA also includes a recommendation to introduce seafood to children when they are around 6 months of age. Seafood is also a potential source of exposure to contaminants that may be harmful to the growth and development of children. Contaminants of particular concern include methylmercury (MeHg), persistent pollutants, such as per- and polyfluoroalkyl substances (PFAS), dioxins, polychlorinated biphenyls (PCBs), and microbiological hazards.

The U.S. Food and Drug Administration (FDA) and U.S. Environmental Protection Agency (EPA) published “Advice About Eating Fish: For Those Who Might Become or Are Pregnant or Breastfeeding and Children Ages 1–11 Years” (also known as the FDA/EPA Fish Advice) (FDA, 2021). This advice is intended to help those who might become or are pregnant or breastfeeding as well as parents and caregivers who are feeding children to make informed choices about the types of fish that are nutritious and safe to eat. In the advice, “fish” refers to both finfish and shellfish from both marine and fresh water sources. The FDA and EPA recommendations serve as the foundation for the DGA advice. Health Canada maintains a website, “Mercury in Fish—Questions and Answers,” that provides consumption advise to the population. The advice is centered around MeHg in various species of tuna and other fish commonly consumed by Canadians.² FDA, EPA, and the National Oceanic and Atmospheric Administration (NOAA) requested a more holistic review of the role of seafood in the diet—with consideration of components found in seafood that are potentially detrimental (e.g., MeHg, PFAS, dioxins, and PCBs) as well as those that are beneficial (e.g., essential nutrients)—to evaluate their respective, interacting, and complex roles in child development and lifelong health. The goals are to have

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¹ Throughout the report, seafood consumption guidelines refer to the recommendations in the Dietary Guidelines for Americans. This clarification was added after release of the report to the study sponsor.

² Available at: https://www.canada.ca/en/health-canada/services/food-nutrition/food-safety/chemical-contaminants/environmental-contaminants/mercury/mercury-fish-questions-answers.html (accessed October 14, 2023).

an up-to-date understanding of the relationships between fish consumption in a total diet context and children’s health, and to determine if and how to calibrate the FDA/EPA Fish Advice in the future.

In addition, the Closer to Zero Action Plan, launched by FDA in April 2021, sets forth FDA’s approach to reduce exposure through food to four metals (arsenic, lead, cadmium, and mercury) that can have adverse effects on child development, particularly neurodevelopment (FDA, 2023). The agency’s goal is to work with other federal partners to help reduce the concentrations of toxic elements in the blood of infants and children by decreasing exposure from foods containing them (Mayne, 2023).

In 2004, NOAA, in collaboration with FDA and EPA, asked the Institute of Medicine (IOM) to examine the relationships between risks and benefits associated with seafood consumption through a consensus study to help consumers make informed choices. The findings were published in Seafood Choices: Balancing the Benefits and Risks (IOM, 2007). That report concluded that the ability to quantify benefits and risks and benefit–risk interactions at that time was limited. The report articulated an approach to balance the benefits and risks of seafood consumption whereby expert judgment was used to produce a qualitative scientific benefit–risk analysis. The analysis relied on the health benefits of omega-3 fatty acids alongside the health risks of toxic contaminants, with the latter based on some available data for MeHg and very little on persistent pollutants.

When the IOM (2007) study was conducted, the systematic review methodology that is relied on today as a gold standard in evidence review was not as commonly used as it is now. Recent systematic reviews use rigorous and transparent methods to search for, evaluate, analyze, and synthesize all relevant research studies to answer specific scientific questions. Given that more than 15 years have passed since the National Academies’ last scientific review on seafood and health, scientific evidence has grown substantially, and robust systematic review methodologies now exist, the time is right for an updated evaluation of the totality of evidence on seafood and its relationship to health.

COMMITTEE’S TASK AND APPROACH

The U.S. Department of Agriculture (USDA), FDA, EPA, and NOAA asked the National Academies to review the role of fish and seafood in the diet, considering components that are potentially detrimental (e.g., MeHg, PFAS, dioxins, and PCBs), as well as those that are likely beneficial (e.g., essential nutrients) and evaluate their respective, interacting, and complex roles in child development and lifelong health. Specifically, the National Academies was asked to convene a committee of scientific experts in the disciplines of nutrition, toxicology, and evidence synthesis to study the associations between seafood intake (maternal and child) and child growth and development. The committee’s task includes:

• evaluating dietary intake and seafood composition data provided by the co-sponsors,
• conducting systematic reviews of the scientific literature covering the areas of seafood nutrition and toxicology,
• reviewing existing sources of evidence on seafood consumption and child growth and development, and
• integrating the available evidence using existing, adapted, or new evidence synthesis methodologies, where warranted.

The committee’s findings will be used to inform the federal government on the state of scientific evidence on types (e.g., based on species/variety and nutrient and contaminant composition) and amounts of seafood to consume to support healthy growth and allow children to attain their full development. The committee’s statement of task is shown in Box 1-1. In response to the request from FDA, USDA, EPA, and NOAA, an expert committee was appointed to review the evidence, conduct systematic reviews, and recommend amounts of seafood to consume to support healthy child growth and development.

Interpretation of the Task

As the committee reviewed, discussed, and interpreted its task, it determined that including data from Canada in addition to the data from the United States would be useful to understand the context of seafood consumption in the target population groups. Additionally, because the United States and Canada are important trading partners

for seafood, knowledge and understanding of consumption patterns and availability of seafood across both populations is important.

This approach allowed the committee to consider a broader range of data on otherwise relatively small populations. In addition, the committee determined there was a specific need for evidence on at-risk population groups, principally Indigenous peoples and subsistence fishers. Many of these groups share waterways between the United States and Canada as well as common heritage and backgrounds, particularly between Alaska and the Northern Territories. Thus, the committee sought to be inclusive of populations in both countries to better understand their relationships with fish and seafood as a common dietary resource. The committee’s task, however, did not specify inclusion of Canadian populations and therefore these populations were not included in the recommendations.

The committee determined that in this report the term “fish” refers to both finfish and shellfish (e.g., pelagic, demersal, freshwater), mollusks (including cephalopods), and crustaceans from both marine and freshwater sources. Similarly, the term “seafood” is used in the same context, consistent with its use in the DGA (USDA and HHS, 2020). The committee did not consider sea mammals and seaweed to be included in its task.

Approach to the Task

The committee evaluated data and evidence submitted by the study sponsors, supplemented with additional searches of existing databases and published literature. The committee contracted with Texas A&M University to conduct an update of two previously published systematic reviews provided by the sponsor: one on seafood consumption during childhood and adolescence and neurocognitive development, and the second on seafood consumption during pregnancy and lactation and neurocognitive development in the child. In addition, consultants to the committee with expertise in systematic reviews developed a protocol that was carried out by Texas A&M

University for a de novo systematic review on toxicants in seafood and neurocognitive development in children and adolescents. The protocols for the systematic reviews are in Appendix C.

The committee also gathered information from publicly available data sources, including both original research and systematic reviews from the published peer-reviewed literature. The committee commissioned analyses from the Johns Hopkins Center for a Livable Future at the Bloomberg School of Public Health of seafood consumption and nutrient intake in the target population groups using data from the U.S. National Health and Nutrition Examination Survey (NHANES). The committee also assessed data from the Canadian Community Health Survey. The committee also held two public workshops to obtain additional information relevant to its task.

ORGANIZATION OF THE REPORT

The report is organized into seven chapters. In this chapter, the background for the study, the statement of task and the study strategy are described. In Chapter 2, the committee elaborates on its methodological approach to the task. Chapter 3 describes data on seafood consumption patterns in the United States and Canada. Chapter 4 reports the committee’s analysis of dietary intake and nutrient composition of seafood. Chapter 5 discusses exposure to contaminants associated with consumption of seafood. Chapter 6 discusses relationships between seafood consumption and health outcomes. Chapter 7 presents the committee’s guidance on the use of risk–benefit analyses to guide the sponsor’s decision making about public guidance on seafood consumption. Biographical sketches of the committee members are provided in Appendix A. Workshop agendas are presented in Appendix B. Appendix C presents details of the commissioned systematic reviews. Information on the supplemental reviews of systematic reviews is given in Appendix D, and Appendix E presents the methodology for the NHANES data analysis. Three additional appendixes are available online.³ Online Appendix F contains the search terms and results for the literature searches conducted for the commissioned systematic reviews. Online Appendix G provides the search terms and results for the supplemental literature searches. The final report from Texas A&M University on the commissioned systematic reviews is found in Online Appendix H.

REFERENCES

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³ The online appendixes can be found at https://nap.nationalacademies.org/catalog/27623.